As for the original post:
I would say, from my belief, that Nidhoggr is a vital part of the circle of life and therefore deserves to be honored. However, I've not heard of many Heathens (even Rokkatruars) that actually "worship" Nidhoggr, simply because it doesn't seem to be a deity that takes much notice of whether or not people are paying it attention (much like Fenrir).
In a way, you could consider Nidhoggr to be an underworld deity. Some people get too technical and want to debate this, or whether Fenrir should be counted as a deity, or whether there are certain Jotun or Alfar or other spirits that are considered "deity" level. In the end, they are all wights (spirits) and can be worked with or honored or worshipped as such, if you so desire to.